Retrieving Individual Characters

Here's my two tables:

tblClients
--------------------------------------------------
ClientID (varchar(3)) | ClientName (varchar(100))
--------------------------------------------------
001 | First
002 | Second


tblProjects
---------------------------------------------------
ProjectID (varchar(6)) | ProjectName (varchar(100))
---------------------------------------------------
001001 | First Project1
001002 | First Project2
002001 | Second Project1
002002 | Second Project2




As you can see, the ClientID is the first 3 digits of the ProjectID, signifying that a certain project belongs to that client. I know it's a bad design, but I can't change the DB, I have to use it.

The problem is that I need to join the two tables based on the ClientID, but I don't know how to just retrieve the first 3 numbers in the ProjectID.

I need something like:
tblClients INNER JOIN tblProjects ON
tblClients.ClientID = tblProjects.First3DigitsOfTheProjectID