You have this twice:

$vacatures =

To show all look at the "like" clause and "%".
Better to have an option where user can search or display all.
Showing all looks something like this, you may also want to paginate large resultsets:

public function ownerlist()
	{
	if(isset($_REQUEST['t1']))
        {
            $t1 = $_REQUEST['t1'];
        }
        else
        {
            $t1 = "";
        }
        $ownersearch = $t1;
        $ownersearch = $ownersearch . "%";
        $data['owners'] = DB::table('powners')
                        ->where('oname', 'like', $ownersearch)
                        ->orderBy('oname', 'asc')
                        ->Paginate(5);
        $data['osearch'] = $t1;
               
        return View::make('owner/pownerlist')->with('data', $data['owners'])->with('data2', $data['osearch']);

Not your data I know, but just an example of like clause.
You may have to chain wheres, examples are in the manual.