Is there a pattern to inform the user to enter the full search string before hitting the search button?

I would like my users to enter a full search value in a field like User ID, before clicking the Search button. This is because, a prefix, or a wildcard could bring in a whole lot of results, and in turn, slow the system down.

Any suggestions of patterns used to call out that a search fields requires the legit value before the user goes about searching would be greatly appreciated. Thanks in advance.