Search form query adjustment

Hello,

in my search form using custom fields addon, I only have 2 fields adverts_category and adverts_location fields enabled, I removed the (Search for ads by keyword …) field.

Now how can I make the search form to query for either the adverts_category and adverts_location fields or both together without searching for any specific keyword.

I want the search result to be delivered based on the search taxonomy in either adverts_category and adverts_location fields.

Example, selecting cars category in search form and clicking search button should output all search results on car ads.

or selecting cars category in new york location in search form and clicking search button should output all search results on car ads in new york.

Thanks