$re = '/ng-click="vm\.onClickTab\((.*?)\'\)/';
$str = ' ng-click="vm.onClickTab(\'wanted\')"';
$subst = "ng-click=\"vm\.onClickTab\($1', $event\)";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
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