You are from HR and your question as what I understood is very basic for HR.
No labour law is depending on type of company but on number of employees you engage. Some labour laws are applicable to specific industry only.
Basic labour law applicable to your contracting firm is S&E Act.
Contract Labour Act is applicable to your work places not belonging to you but belonging to the person or company who gives you the work, subject to having required number of employees at a particular work place.
Other than this, you have to comply various labour laws relating to wages, relating to social securities, relating to EHS & working condition & relating to IR.
You are requested to study all this Acts and if you have any query specific, you are welcome to ask it on this forum. Every HR must know at least the basic features of labour laws. Why at least the basic features? HR must be SUPREMO.
19th July 2018 From India, Mumbai