None of the given sizes seems to fit me perfectly; can I have a custom fit?

Yes, of course. You can select “Made to Measure” in size options and can provide your body measurements. In case you're unsure of your body measurements then you can select "I am not sure, I'll provide measurements later on email" and place the order without any hesitation.
Once your order is placed, our customer support representative will get back to you and will guide you on taking your correct measurements.