The second paramater for date() is a timestamp, so you'll want to turn your existing date into that.
<?PHP
$date = "2003-05-09"; #assumed to be yyyy-mm-dd
list ($year, $month, $day) = explode("-", $date);
$timestamp = mktime(0, 0, 0, $month, $day, $year);
$date_req = date("d M y", $timestamp);
echo $date_req;
?>