The directory plugin creates a search box on your site. It

The directory plugin creates a search box on your site.

It seems to allow searching of listings titles/bodies but nothing else.

How could I extend the search to tags that one can add to the listings we create.

Also, extend the search to listing custom fields?

Seems reasonable if you have custom fields that include phone or city that this should be searchable.

Is there some reason this is not default behavior? Hard on database? or something I am missing?