looking for the latest multiSearch.php

Hi. The last forum posts with the full multiSearch.php code are from 2013 and some people were having issues with pagination, etc. Trying to determine which file to start with and what edits should be done would be rather time consuming. Does anyone have a complete, current file, that they could post here?

If this could ever be converted to a plugin, that would be much welcomed!

Thanks in advance for any help.

~ Deborah