Refining Custom Properties results

Hello-
I am having a problem refining my searches. I have a field named "Amenities" and seven different possible values (hot tubs, fireplaces, etc.). I would like to show results that match completely, as in hot tub AND fireplace. Currently the results are showing any article with a hot tub OR a fireplace, not necessarily both. Is there any way I can change this?

Thanks!

The right field type for "Amenities" is 'AND multiselect" or "AND multiselect + Picker" (I'd recommend the latter)