This can be done in the configuration of your DVR. I'm using the DS7208HUHI but the procedure should be similar on other models.
Logon to DVR select configuration then user.
Set up a new account with the name guest or any name you prefer.
Click the permissions icon
Click camera config
Tick the cameras you wish the guest account to view
Apply the settings
Now access the 4500 client on your tablet/smartphone and logon with the guest name and password.
The guest user should now be able to view the permitted camera only.
Hope this helps.
Geoff.