The Field Permissions module CodeNext propose is nice because it will allow you to define witch fields are available for witch role.
However, it can be also really interesting for you to look at the Node Option Premium module, witch allow you to define roles with proper privileges to view the full content of the node.
User without the proper permission will only see the teaser of your content and a message saying this content is reserved for members.
When a node is published as premium content, only users with proper
privileges may view the full content of the node.
Non-premium users can still access premium nodes but only get the
content rendered in teaser context, even when trying to view the full
content. An additional message informs them that the content is
available to premium users only.
You can also use both module together (Field Persmissions and NOPremium), and also have some fields shown to specific roles.