The recommended way to is via Composer:
composer require surda/logging
$stack = \GuzzleHttp\HandlerStack::create();
$stack->push(
\GuzzleHttp\Middleware::log(
new \Surda\Logging\TracyGuzzleLogger(),
new \GuzzleHttp\MessageFormatter('{request} - {response}')
)
);
$client = new \GuzzleHttp\Client([
'handler' => $stack,
...
]);