Example
$service = new NetSuiteService();
$search = new TransactionSearchAdvanced();
$internalId = '123';//transaction internalId
$search->criteria->basic->internalIdNumber->searchValue = $internalId;
$search->criteria->basic->internalIdNumber->operator = "equalTo";
$CustomSearchRowBasic = new CustomSearchRowBasic();
$CustomSearchRowBasic->customizationRef->scriptId = 'custbody_os_entered_by';//this is specific to you & found in netsuite
$CustomSearchRowBasic->searchRowBasic = new EmployeeSearchRowBasic();
$CustomSearchRowBasic->searchRowBasic->entityId = new SearchColumnStringField();
$search->columns->customSearchJoin[] = $CustomSearchRowBasic;
//and so on, you can keep adding to the customSearchJoin array the custom fields you want
$request = new SearchRequest();
$request->searchRecord = $search;
$searchResponse = $service->search($request);
