Once you get your student certificate from student affairs or from Orion, you can purchase “İstanbul Kart” to use public transportations. 
https://bireysel.istanbulkart.istanbul/

Required documents
•    Student certificate taken within the last 1 month confirming that you are a student
•    Original identity card or passport
•    Current passport photo

CURRENT APPLICATION CENTERS

You can find the list of current application centers in the link below. 
https://www.istanbulkart.istanbul/applicationCenters