Creating a "Search" sheet that will search through multiple xls sheets in subfolders?

I work in an office of about 500 people, with a lot of paperwork being sent around multiple departments.

Because of this, important documents are frequently misplaced, so I am attempting to create a system of spreadsheets to help track what is on a persons desk at any given time.

Unfortunately, it's pretty much all in my head so far!

Each person would have a simple spreadsheet of their own, named "John Doe.xls" or whatever, and this would contain all of the categories and serial numbers of the cases that they were currently dealing with.

This would be in a folder named after their team, or department, or floor of the building, and all of these would be able to be searched through by one master sheet, so that anyone could enter a serial number and it would reveal what people currently had work relevent to that case on their desk.

I'll try to attach the template I'm using right now... apologies for the garishness!

Currently I'm searching through them by using Windows "Search for Files and Folders" and using looking for the serial number as "a word or phrase in the file" and it works, but it really isn't ideal, and I'd like to make the whole thing idiot-proof so that people with zero experience could use it.

I hope all of this makes sense... It really would make life a lot easier for everyone in the building!

Thanks a lot for reading all this anyway