I am not a very big fan of apple. But I heard that 5s is only having a 4 inch display. so will it worth buying in 2016? will I able to manage it? Will it suit for me? Thank you.
Based on your needs it might be worth it. If a 4 inch display is what you're looking for then the SE may be a better option, since it's a newer device.
If you are not a big fan of Apple maybe you want to look into another device. I get you want a smaller screen but if iOS isn't something you like then don't get an iPhone. No one can answer what will suit you other than you. That all being said IF you decided to get an iPhone go with the SE. The 5s is 3 year old technology.