Friend I am in Karachi, their is very famous wind screen shop at plaza it is opposite to Plaza if you are comming from Mazara Quaid than from Tibet Center take u turen and it will come on your left side.
After taking you turn you can ask some shop it is very close big shop of wind screen, they have all the qualities available in the market and they can arrange some guy to go with you and install it at your place. (they will charge for it i believe 500 Rs or 1000 Rs for installing at your place)
Their dealing is very good please do visit