How to design:Use One TCPIP Client connection to Server and work concurrently

[ray]

Hi all,
  Because the server only can accept ONE connect from client.
If the client establish  connection with the server,the server can not accept other client.
One large batch transaction file come from user.
client divide the large file to several smaller files.
In my thinking:
client have many seats.Each smaller files is thread.
client manage which seat was avaiable,handle send to/recv from server.
Any idea or suggestion?