You forgot to add the space between ’ and /home/user/install in sed command.
Also I don’t see the escape symbols (\) in the sed command "\$@".
Once again try:
sed -i 's|https_proxy=http://127.0.0.1:8082/ http_proxy=http://127.0.0.1:8082/ wget --no-check-certificate -nv "\$@"|sh -c "https_proxy=http://127.0.0.1:8082/ http_proxy=http://127.0.0.1:8082/ wget --no-check-certificate -nv \\\"\$@\\\""|g' /home/user/install