An Account Executive can (in the context of creating an order) request Script Approval and/or Spot Approval in the Creative Details section of the Order entry screen. 

Similar to the default Order Settings that can be configured by the Administrator, the Account Executive may also choose to have the Writer send the script to the client for review and/or have the Producer send the spot to the client for review by selecting these options when creating the order.

By default the script review and/or spot review requests are sent to the client by the Account Executive (when they are ready for review).