iOS 9.3 (build 13E237) is an official Apple over-the-air update for the iPhone 4s, released on 2016-03-28T16:52:19Z. The update package is 197.25 MB. This is a delta (partial) update that requires 9.2.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 8f0ee5f75e4495d213bd99f97d37a6018dc11f81.zip.