multimailbox search ex2013

Dear Friends...

I have a requirement with one of the client where the current mail box system gives them facility to look into all user mailbox and give a criteria and on the web browser only they get mail conversation which has happened though out their all user mailboxes. Now i am bringing them to Exchange and i am not sure how will i be able to achieve this as ... they have two requirements as follow :

1. each user should look into each other mail box when search is done for specific client or mail.

2. Managers can look into their specific team members mailbox and search any mail.

They also want mi to create this grouping which i mentioned in point 2 above so to have multiple groups and each group can have one admin which can do the multi mailbox lookup..

Please guide friends is this is possible and how this can be achieved...