Dear student!
Yes, a Student, if failed even in one subject exam, is considered as fail or rather say, gets compartment. So, definitely it's a fail, if you fail in three subjects. But, there's also a provision of compartment exam where you can re- attempt the paper and then your score is calculated accordingly. Offcourse the question paper changes from the previous one, but is on same syllabus. So, you can apply for re attempting the exams. Hope this helps.
Good luck!