Using custom field to request posts

Does anyone know the code to use in a <a href=...> link that will call only posts with a specific custom field in the custom template page called by the link? I have several graphic images that all link to separate wp pages. Each of those wp pages uses the same custom template. I want each image to only call posts that have a particular custom field key:value and display those. I need to figure out how to then pass that variable from the href link to the template page code so that only specific posts are displayed correlating to the particular image link clicked on. Can anyone help with this? Thanks!