Hi,
Taxonomies are not custom fields – they are two separate things.
While I am not sure what do you want to achieve, I can link some documentation that may help you out. If you want to create filters on taxonomies (attributes), then the taxonomy term filters is what you need.
If you want to search the taxonomies (attributes), then this is what you are looking for.
If you want to display the taxonomies or custom field values in the live results list, then this will help.