Hi there. 

It is great to know that you are a determined student who is working so hard towards a bright future and career. 

To be honest, CA is enough for you to have a great, fulfilling and successful career. CA demands a lot of patience, hard work and time. 

During your articleship, you'll be so tired by the end of day that you wouldn't get any time to pursue another course. 

For the sake of your question, if you really want to take up an Arts Course then I'd suggest doing Law. 

But you can only do Law full time. There are a lot of universities like Delhi, Mumbai, Allahabad etc that offer a 3 year LLB course. You can check those. A law degree would be a grea option for a CA candidate.

Other than this if you have any particular art course in mind and have any doubts regarding it you can surely post your query here. We'll be happy to help. 

Hope this helps.