Client Login Questions

I’ve been looking for some plugins but I can’t seem to find what I’m looking for. What I’m looking for is this:
Client would go to client.mydomain.com and be prompted for a username and password and once they entered it, they’d be shown and posts/pages that would belong to them. For instance, if I was to do a video for a client, they go to this page, login and be shown and video versions I’ve posted restricted only for their viewing to receive comments. I’d then post v2 and so forth. So lets say after 3 versions, when they logged in, they’d see the 3 versions in 3 different posts w/ all comments related to them. Does this make sense?

I’m hoping someone has some ideas or advice as to where some solutions may lie. I’d rather not have the login redirect to a page. I’m hoping to keep it so all they see in the url is client.mydomain.com just logged in as their username w/ their appropriate posts/page.