$re = '/(?<=\b\w+=\()[^)]+(?=\))/m';
$str = 'title=(example1) caption=(example2) button=(example3) price=(example4) off=(example5)
lorem ipsum this is ignored magic=(happens) here! :)';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php