using (System.IO.Stream fileStream = System.IO.File.OpenRead(m_strFilePath))
{
    Microsoft.SharePoint.Client.File.SaveBinaryDirect(m_clientContext, str_URLOfFile, fileStream, true);
    Microsoft.SharePoint.Client.File fileUploaded = m_List.RootFolder.Files.GetByUrl(str_URLOfFile);
    m_clientContext.Load(fileUploaded);
    m_clientContext.ExecuteQuery();
    User user1 = m_Web.EnsureUser("User1");
    User user2 = m_Web.EnsureUser("User2");
    ListItem item = fileUploaded.ListItemAllFields;
    fileUploaded.CheckOut();
    item["UserDefinedColumn"] = "UserDefinedValue1";
    item["Title"] = "UserDefinedValue2";
    item["Editor"] = user1;
    item["Author"] = user2;
    item.Update();
    fileUploaded.CheckIn(string.Empty, CheckinType.OverwriteCheckIn);
    m_clientContext.ExecuteQuery();
}

$web = Get-SPWeb "site URL"

$list = $web.Lists["List Name"]

foreach($item in $list.Items){

    $itemAtual["Created"] = "Created Date"
    $itemAtual["Author"] = "Author ID"
    $itemAtual.Update()

}