bitcoin-cli "error: couldn't connect to server"
The --* arguments to bitcoin-cli should come before the RPC command. Those arguments are for bitcoin-cli itself. However the position you put them in are positions for the getinfo RPC command and not bitcoin-cli. You should instead be using the following command:

.\bitcoin-cli.exe --rpcport=54352 --rpcuser=admin --rpcpassword=admin123 getinfo