You cannot restore an iOS 9 iCloud or iTunes backup onto iOS 5. You must set up the phone as a new device. Preparation Checklist
Download the IPSW files for the iPhone 4S (iPhone4,1) for both iOS 5.1.1 and iOS 7.1.2 from a trusted source like ipsw.me. downgrade iphone 4s to ios 5
While a direct downgrade to iOS 5 is difficult and generally requires saved from when that version was current, there are community-developed tools for "tethered" or "un-tethered" downgrades: You cannot restore an iOS 9 iCloud or