Hi!
It’s a feature I had honestly forgot to implement 🙂
Instead of writing a rather long guide on how find the lines and files to modify, I’ve quickly implemented this feature on my test environment, it seems to be working correctly. All you need to do is simply change all the contents of the wp-contents/plugins/ajax-search-pro/includes/classes/search/search_terms.class.php file to this on your server: https://goo.gl/OGFGq8
I hope this helps!