Try using preg_match
if (preg_match("/men/i", $class)) {
echo "A match was found.";
} else {
echo "A match was not found.";
}
Look at this link for more information http://www.php.net/preg_match
Edit :
So you can do like this (Inspired from the answer of Marius.C)
$string = '<div class="menlook">Some text</div>';
if (preg_match('/class="(.*)men(.*)"/i', $string)) {
echo "A match was found.";
} else {
echo "A match was not found.";
}