I'm pretty sure I have already read this somewhere, but I just can't find it anymore. There are a couple of apps which are found by searching after some defined keywords in the iOS Home Screen search while these keywords differ from the app name. Have a look at this example:
How can I do this?
Spotlight searches the full app name, not only the one you see in the springboard but the one showed on iTunes. The full app name in this case is "barcoo ‐ Produktguide mit Barcode Reader & QR Scanner" so you can find it simply searching the word "scan" which is contained in "scanner"