In Mac OS X, does Spotlight search Stickies?
“If you haven’t noticed by now, Spotlight does not index the notes that Stickies creates. This is at least in part because Spotlight indexes files by their extension, and each file extension should map to a unique Uniform Type Identifiers (UTI). Unfortunately, Stickies stores all of its information in ~/Library/StickiesDatabase: a single file encapsulating multiple notes that has no extension.”
The article below then goes on and tells you the steps involved in using Xcode to create a Spotlight plugin that will get Stickies to show up in Spotlight searches. Xcode is one of the free Developers Tools available from Apple.