$search = "test1"; //later to be changes to $_POST ['search'];

$sql = "SELECT id, name FROM clients WHERE name LIKE CONCAT('%',:name,'%')";
$stm = $db->prepare ($sql);
$stm->bindParam ( ":name", $search );
$stm->execute ();
$result = $stm->fetchAll();

$query = "SELECT id, name FROM clients WHERE name like :name order by id LIMIT 5";

$sql->execute(array(":name" => "%" .$search . "%"));

LIKE CONCAT('%', :name, '%')