Send files from Pen Drive to PHP server

Hello, I'm using Arduino UNO. WiFi Shield, USB shield are connected with it. Arduino is taking data from GPIO and storing it in excel file and text file. I want to send these files to a computer via WiFi. A computer will be hosting XAMPP server and requests are made from the web page. Whenever the request is made, Arduino should send the files to the server.

I just wanted to know that is this possible. If possible, someone can please show me the way to do it.

Thanks in advance.

Webservers are not meant to send requests to a client, so could you elaborate that part?

lg, couka