I came up with this idea working with a user who has a very extensive list of parts with their associated part numbers.
The Problem: The user wanted to be able to search by either the part description, or the number (instead of just one of those items).
The Solution: Create a copy of each field with it's associated reference data. (I found it helpful to label each set of fields based on how we were searching). For the first set, have field A (parts number) initiate the flow of data (this is the drop down we will be searching), and have the description field reference the part number. . For the second set, set it up in the opposite order: Description will initiate the flow of data, and Parts Number will reference the Description.
Then, add a field (either a drop down or a multiple choice field) allowing you to select which method you would like to search by. I put this field at the top of the screen.
Add a condition to the fields with the reference data that allow the proper fields to appear based on which type of search you'd like to do (see screenshot below):
Once you've set up your reference data and conditions properly, you're ready to save and publish!