How to write career change cover letter?

Hey Folks!

I have PhD in microbiology and molecular genetics, most of my experience is wet lab, some bioinformatics but not much..

I've been working on machine learning and data analysis career path for the last 6 month and I think I'm ready to start applying. The big problem is the cover letter - I don't know how to justify the career change? Are there any good tips for me to write a good and convincing cover letter?

Another problem is that my IT experience is nowhere close to the guys who have PhD or even MS in bioinformatics or computational biology, that is something that I also need to address?

I would love to hear your thoughts!

Thanks!