using (clientContext)
        {
            Microsoft.SharePoint.Client.File page = clientContext.Web.GetFileByServerRelativeUrl(pageUrl);
            clientContext.Load(page);
            clientContext.ExecuteQuery();

            if (page.CheckOutType == CheckOutType.None)
            {
                page.CheckOut();
            }
            var wpm = page.GetLimitedWebPartManager(PersonalizationScope.Shared);
            clientContext.Load(wpm.WebParts);
            clientContext.ExecuteQuery();

            if (wpm.WebParts.Count != 0)
            {
                foreach (WebPartDefinition webpart in wpm.WebParts)
                {
                    webpart.DeleteWebPart();
                    clientContext.ExecuteQuery();
                }
            }

            var importedWebPart = wpm.ImportWebPart(webPartSchemaXml);
            var webPart = wpm.AddWebPart(importedWebPart.WebPart, zoneid, zoneIndex.ToInt32());
            page.CheckIn("", CheckinType.MajorCheckIn);

            clientContext.ExecuteQuery();

        }

function ChangePageLayout()
{
    param(
        [Parameter(Mandatory=$true)][string]$siteurl,
        [Parameter(Mandatory=$false)][System.Net.NetworkCredential]$credentials,
        [Parameter(Mandatory=$false)][string]$PageName,
        [Parameter(Mandatory=$false)][string]$PageLayoutName,
        [Parameter(Mandatory=$false)][string]$PageLayoutDisplayName,
        [Parameter(Mandatory=$false)][string]$Title,
        [Parameter(Mandatory=$false)][bool]$isCustomPageLayout
    )
    try
    {

        $ctx = New-Object Microsoft.SharePoint.Client.ClientContext($siteurl)
        $ctx.Credentials = $credentials

        if($isCustomPageLayout -eq $false)
        {
            $PageLayoutName = "/_catalogs/masterpage/" + $PageLayoutName + "," + $PageLayoutDisplayName
        }
        else
        {
            #Here I have assumed that if its custom page layout, then it's placed inside some folder which is child to masterpage
            #If that's not the case with you then you can use below line of code
            #$PageLayoutName = "/_catalogs/masterpage/" + $PageLayoutName + ", " + $PageLayoutDisplayName
            #
            $PageLayoutName = "/_catalogs/masterpage/Custom Page Layouts/" + $PageLayoutName + ", " + $PageLayoutDisplayName
        }

        $Pages = $ctx.Web.Lists.GetByTitle('Pages')
        $camlQuery = New-Object Microsoft.SharePoint.Client.CamlQuery
        $camlQuery.ViewXml = '<View><Query><Where><Eq><FieldRef Name="FileLeafRef" /><Value Type="Text">'+ $PageName +'</Value></Eq></Where></Query></View>'
        $Page = $Pages.GetItems($camlQuery)
        $ctx.Load($Page)
        $ctx.ExecuteQuery()

        $file = $Page.File

        $ctx.Load($file)
        $ctx.ExecuteQuery()

        if ($file.CheckOutType  -ne [Microsoft.SharePoint.Client.CheckOutType]::None) {
            $file.UndoCheckOut()
            $ctx.Load($file)
            $ctx.ExecuteQuery()
        }

        $file.CheckOut()
        $ctx.Load($file)
        $ctx.ExecuteQuery()

        $Page.Set_Item("PublishingPageLayout", $PageLayoutName)
        $Page.Set_Item("Title", $Title)
        $Page.Update()
        $Page.File.CheckIn("", [Microsoft.SharePoint.Client.CheckinType]::MajorCheckIn)
        $Page.File.Publish("")

        #check for approval
        $ctx.Load($Pages)
        $ctx.ExecuteQuery()

        if ($Pages.EnableModeration -eq $true) {
            $Page.File.Approve("")
        }

        $ctx.Load($Page)
        $ctx.ExecuteQuery()
        Write-Host "Update Page Layout Complete"
        Write-Host ""

    }
    catch
    {
        Write-Host ("Error while changing page layout. Error -->> " + $_.Exception.Message) -ForegroundColor Red
    }
}

$credentials = Get-Credential
ChangePageLayout "http:yoursite.com" $credentials "default.aspx" "YourCustomLayout.aspx" "Your Custom Page Layout" "Some Title" $true