In Everything, from the Search menu, click Add to filters....
Change the Name to: My Properties Search
(can be anything you like)
Change the Search to: custom-property-1:$param: | custom-property-2:$param: | custom-property-3:$param:
Change the Macro to: mps
(can be anything you like)
Click OK.
Now you only need to search for:
mps:TestWord
which will expand to:
custom-property-1:TestWord | custom-property-2:TestWord | custom-property-3:TestWord