How can do squid bypass client's request to orign server if 404 error code occured?.

["Seonkyu Park" <carrot@xxxxxxxxx>]

Hi Squid Users.

I'm looking to setup a reverse proxy cache with SQUID if squid can't find pages(html or image) 
then client's request go to origin server. (bypass) 

Example.
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# Current Status.
Step 1.
    Client Request    =>    Reverse Proxy(Squid)  =>    Origin Server(Apache)

Step 2.
    HTTP 404 (Not found event)

Step 3.
    Squid Error code  => 

ERROR
The requested URL could not be retrieved
--------------------------------------------------------------------------------
While trying to retrieve the URL: http://x.x.x.x/asd 
The following error was encountered: 
Access Denied. 
Access control configuration prevents your request from being allowed at this time. Please contact your service provider if you feel this is incorrect. 
Your cache administrator is webmaster. 

* I want change like this

Step 3.
    Show Apache Error code (bypass to orign server)
   
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Thank you very much for your help and advice.