Iphone 5s back glass broken

I boughat iphone 5S from KSA few months ago. it is still under apple warranty. But last day it slipped through my hands and fell on floor which broke lower back glass of phone. I want to know whether apple will claim my warranty or not? Because my phone doesnot turn its flash on during video capturing when it is on auto and sometimes its touch does not respond at all. These issues were occuring before damage. And also I wanna know whether only this glass can be replaced or not?? And how much will it cost me??