We are a service management company which caters to the B2C and B2B markets so we use Accounts for our biz customers and Contacts for our B2C customers. 

In case of a call for a new job from a new customer; I can create a new Account from Cases after lookup fails to find that customer in its list. Similarly in the "Related To" field lookup finds the Contact but one can't search and create a contact on the fly like once can create an account.

Any tips to solve this problem ? or is this a system limitation ?