There are iOS apps that allow you to log into a Mac on the same WiFi network. They display the Mac screen on your iPhone or iPad, and provide a keyboard to log in. Finger can be used as mouse; tap to click.
The Mac must have "Screen Sharing" turned on. I use a free one called "VNC Viewer" and it's worked well for me -- I like it. There are others on the Apps store -- look for "VNC" or "Screen Sharing". Hope I understood your question correctly!