I think I understand a bit better now. You are trying to search Custom Fields for Customer data.
On the General Options->Sources panel, you can select which fields you want to search, I have already selected a few, see screenshot: https://i.imgur.com/u2XDg7M.png
Next, I have created a filter for price as an example. This is how it looks like on the back end: https://i.imgur.com/7PR12GK.png
It shows a slider on the front-end with a range of 1-1000000: https://i.imgur.com/CtuKWga.png
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