Query suggestion multi fields + raw field and with results new created boosted

Hi,
we are trying to query 3 fields for a given text.
3 fields are
body, title and raw-body (not analyzed). title is of the most importance
and then the body and raw-body. if thing matches exactly with raw-body
we want it to be ranked higher. Also if matches are identical in 2
documents we want to use decay function for promotion of fresh content.

Can you please give me some idea how we can write this complicated query?

Thanks in advance.

Regards,
Rahul